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Homing pigeons have a good nose for directions

Scientists have figured out how homing pigeons, or carrier pigeons as they are also called, can find their way back even if they are released hundreds of kilometres from home. The birds are actually equipped with a kind of compass behind their beaks.

PHOTO: GV/PRESS In the old days, homing pigeons were used to carry messages that had to be transmitted quickly or secretly. Homing pigeons have a unique ability to find their way back to their pigeon houses, even if they are transported hundreds of kilometres from home.

Milestones in the landscape

Scientists have known for quite some time that these birds navigate using scent, milestones in the landscape and magnetic forces. However, exactly how the pigeons manage to detect magnetic forces and navigate by them has been a mystery.

Magnetic forces

Planet Earth is a huge magnet and its magnetic forces produce invisible lines that run through the North and South Poles. All substances that are magnetic are oriented on the basis of these meridians, as they are called. One example of this is the needle on a compass, which invariably points north–south.

Compass in their nasal cavity

Researchers have recently found evidence to indicate that homing pigeons have a sort of compass in their nasal cavity which enables them to sense magnetic forces and thus to tell directions. This 'compass' is probably comprised of minuscule particles of metal (magnetite), which work like a compass needle and are guided by the Earth's magnetic field.

Home, sweet home

The researchers put the homing pigeons into a tunnel equipped with an artificial magnetic field, and then they taught the pigeons to jump to the one end when the field was turned off and to the other end when the field was turned on. This shows that the pigeons could tell the difference.

When researchers fastened tiny magnets to the birds' beaks, the pigeons' built-in compasses were disturbed and they could no longer determine what was what. The pigeons also failed the test when their nasal cavities (where their natural compass is located) were anaesthetised.

Unique

The homing pigeons' 'compass' is fairly unique among birds. Other species of birds also register magnetism, but in a different way. The rainbow trout, another species of animal that migrates across incredible distances, has the same type of compass in its nasal cavity as the homing pigeon.